Various kinds of battery constructions utilize a porous battery separator material disposed between the battery electrodes for positioning the electrodes in a spaced apart relationship and to maintain the battery electrolyte in contact with the electrodes. For example, one known construction consists of a wound anode interleaved with a wound cathode, with the wound anode and cathode being spaced apart from one another by a nonconductive porous separator material which is impregnated with electrolyte. Various battery separators have been produced from nonwoven webs of fibrous materials. For example, Williams et al. U.S. Pat. No. 6,174,826 describes a nonwoven battery separator material which is formed from a blend of polypropylene staple fibers and polyethylene/polypropylene sheath/core bicomponent fibers. Published PCT Application WO 00/41254 describes a nonwoven battery separator material which includes thermoplastic polymeric fibers blended with a hydrophilic melt additive.
Although nonwoven webs of this type offer many advantageous features, the need exists for greater control over the uniformity, strength, dimensional stability, electrolyte transport properties and other characteristics of a nonwoven battery separator. For example, it is important that the battery separator have uniformity in thickness and basis weight, avoiding holes or thin areas that could produce short circuits or variations in the resistance or other electrical properties.